People tend to remember their dreams in the morning a little bit better and if earlier in the night, when you're in a lot of deep sleep, if someone wakes you, or the phone rings or something, you're really confused.

So it's like your brain has a large filing cabinet and it's opening up each drawer and it's taking in various images and memories from the day, consolidating what it needs to and puts in whatever file. And then if there's something that doesn't fit in any of the files and doesn't really belong, you'll forget about it. So it's a way of really getting a succinct way of storing things in your brain.

When it comes to the reason why we have nightmares, we're still debating that. It's a new area of research, nightmares. And the way I like to think about it is, our brain - we have stress during the day and our brain needs to learn to process this stress.

We're not really sure why it [broken circadian rhythm] continues, but when they become adults, we usually have to treat it because many people need to get up early to go to work and they can't be sleeping until 11:00 or 12:00. So we use treatments like bright light therapy, melatonin, things like that that are very effective.

Some patients will report that they have sleep paralysis. If we see sleep paralysis alone and nothing else, we don't really think all that much of it, but if we see other symptoms, then it might be a red flag for something else that's going on.

So you have it, you awaken from it and you can recall, in detail, what just happened, that's a nightmare. So it's very different from a dream where you generally don't wake up from it and you don't have this dysphoric emotion.

So when you go to sleep at night, if you're someone who hasn't had any sleep deprivation, you have a very normal sleep pattern, what we tend to see is that, in adults, they go to bed and they start off by going into the deeper stages sleep.